Tree: Usually a straight single trunk, not buttressed, with little taper below the base of the crown. Height to 50 m, dbh to 270 cm. Monoecious (Boland et al. 1985).
Bark: Brown to grey-brown, coarsely flaky, inner bark ('outer blaze') mixed pink and brown with a milky bark exudate and a faint odor of pinene (Boland et al. 1985).
Shoots: Primary (orthotropic) shoots with spirally inserted leaves, secondary (plagiotropic) with opposite to subopposite leaves (Boland et al. 1985).
Leaves: Linear to elliptic, 2-9 × 0.5-2.5 cm, stiff, with fine, longitudinal, subparallel veins, on 1-2 mm long petioles. Seedling leaves ovate-lanceolate, acute, 5-8 × 1.5-2.5 cm, venation and peioles similar to adult (Boland et al. 1985).
Cones: Globular to ovoid, 7.5-11.5 × 6.5-10 cm (Boland et al. 1985).
Cone scales: Size to 2.6-3.5 × 3.3-4.5 cm, numbering 160-210, generally glaucous at the apex (Boland et al. 1985).
Pollen cones: Shortly pedunculate or almost sessile, 1.1-1.6 × 0.6-0.8 cm, with 400-500 scales. Each scale has 2-5 pollen sacs on the abaxial side. Cones mature in December (Boland et al. 1985).
Seeds: Cordate, winged (Boland et al. 1985).
Wood: Heartwood cream to pale brown, growth rings usually inconspicuous, about 480 kg m-3 (Boland et al. 1985).
Other features: Cotyledons 2, oblong or ovate, 2.5-3 × 1-1.5 cm, almost sessile, slightly stem-clasping, with fine, indistinct, longitudinal, sub parallel veins (Boland et al. 1985).
Australia: N Queensland. You can also create a highly detailed map, and access specimen data, using the "search" function at the Australia Virtual Herbarium.
Almost entirely confined to rainforests of the Atherton Tableland, at latitude 17-18° S and elevations of 400-900 m. The mean maximum temperature of the hottest month is 30°C and the mean minimum of the coldest month is 10°C (data for Atherton station). Precipitation is 1400-3300 mm, concentrated in the summer months, reaching a minimum of 25 mm in the driest month (August or September). Soils are deep loams to clays on varied silicic substrates. As with most species of Agathis, it grows as a rainforest emergent in a canopy composed of hundreds of different tree species (Boland et al. 1985).
The WCMC states that "As with A. atropurpurea, this timber species is found in low densities in localised lowland rainforest. Logging is heavy where the forest is unprotected. Before 1985 the population had been halved by logging but 70% of the forests are now protected."
Said to attain heights of 50 m and diameters of 270 cm; perhaps this was true historically, as no trees now living are known to attain such sizes (Boland et al. 1985). The "twin kauris" at Lake Barrine, Crater Lakes National Park in North Queensland, are quite famous as the largest conifers in Australia. The larger of these trees was measured in 2002 as 205 cm dbh and 41.2 m tall (Robert Van Pelt e-mail, 2003.01.27), and in 2009 as 215 cm dbh and 40 m tall (National Register of Big Trees 2012). The tallest known, 60.0 m (measured in 2009), is in Barron Gorge National Park, Queensland. I don't know how it was measured. Such a round number suggests that it may have been an estimate; the tallest tree that I know to have been measured by laser or tape drop is the 41.2 m tree mentioned above.
It has apparently not been examined, probably due to its very limited distribution.
The timber is soft, light, easy to work and polishes well. It is not durable in contact with the ground, but is used for house framing, flooring, and joinery (Boland et al. 1985).
See "Big Tree" above.
The specific epithet microstachya derives from the Greek micros (small) and stachys (ear of corn or a flower spike), alluding to the small male strobili (Boland et al. 1985).
National Register of Big Trees. 2012. Tree Register: National Registry of Big Trees. www.nationalregisterofbigtrees.com.au, accessed 2012.06.23.
The species account at Threatened Conifers of the World.
Last Modified 2017-12-29